Patterned Li-S Battery Cathode for Higher Volumetric Energy Density
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Solution Overview
Problem
The challenge in lithium-sulfur secondary batteries is to improve the energy density per unit volume without compromising the material movement characteristics, as increased porosity in the positive electrode leads to a decrease in energy density and volume expansion.
Innovation Solution
A positive electrode active material layer with an intaglio pattern is formed by laser patterning, maintaining a porosity of 50 to 65% and adjusting the intaglio pattern's width, depth, and spacing to enhance material movement and reduce volume while preserving electrolyte impregnation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the porosity of the positive electrode is increased to improve material movement characteristics, then the energy density increases, but the volume of the positive electrode increases, resulting in decreased energy density per unit volume
Solution Approach 1:
The patent applies laser patterning to create three-dimensional intaglio patterns on the electrode surface, transforming a two-dimensional flat structure into a three-dimensional textured structure. This dimensional change allows the electrode to maintain high porosity for material movement while reducing the overall volume occupied by the electrode, thereby improving energy density per unit volume.
Solution Approach 2:
The patent utilizes porous carbon materials with controlled porosity (30-50%) in the positive electrode structure. The porous structure facilitates movement of polysulfide and lithium ions while the laser-formed intaglio patterns optimize the distribution and accessibility of these pores, enabling high energy density without excessive volume increase.
2Ease of operation
If the porosity of the positive electrode is increased to improve material movement characteristics, then the wettability with electrolyte solution improves, but the volume of the positive electrode increases
Solution Approach 1:
The laser patterning process creates intaglio patterns that add vertical dimension to the electrode surface, increasing surface area and improving electrolyte wettability without proportionally increasing the horizontal footprint or overall volume of the electrode assembly.
Solution Approach 2:
The intaglio patterns create localized regions of enhanced porosity and surface area where electrolyte interaction is most needed, while other regions maintain optimized density. This local quality variation improves overall wettability without requiring uniform volume increase throughout the entire electrode.
3Area of stationary object
If laser patterning is applied to increase specific surface area for improving wettability, then the surface area increases, but the manufacturing complexity increases
Solution Approach 1:
The patent replaces complex mechanical patterning methods with laser patterning technology. The laser beam can be precisely controlled to create intaglio patterns directly on the electrode surface without mechanical contact, tooling, or multiple assembly steps, significantly reducing manufacturing complexity while achieving high surface area.
Solution Approach 2:
The laser patterning process allows dynamic adjustment of pattern parameters (depth, width, spacing, geometry) through software control of laser parameters such as power, speed, and scan patterns. This parameter flexibility enables optimization of surface area without requiring complex physical tooling or process changes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly improves energy density per unit volume and maintains discharge capacity, ensuring uniform material movement and electrolyte penetration, even with reduced positive electrode active material content.
Implementation Method 1
the intaglio pattern is obtainable by irradiating the positive electrode active material layer with a laser to remove a part of the positive electrode active material layer
Data Source
Figure 1a~1c
Figure 1d~1f
Figure 2~3
AI summary
A positive electrode for a lithium-sulfur secondary battery comprising a positive electrode active material layer having an intaglio pattern formed therein, a method for manufacturing the same, and a lithium-sulfur secondary battery comprising the same are provided. The positive electrode active material layer has a porosity of 50 to 65%. The intaglio pattern has a width of 1 to 100 µm and a depth of 30 to 99% based on the thickness of the positive electrode active material layer. The volumetric ratio of the positive electrode active material layer and the intaglio pattern is 4:1 to 40:1. When the positive electrode is applied to a lithium-sulfur secondary battery, the energy density per unit volume can be remarkably improved.